Hexafluoro-1,3-butadiene (referred to “C4F6” or “HFBD” in this specification) is noted as, for example, an etching gas for semiconductor fine processing.
The following methods are conventionally known as a process for producing hexafluoro-1,3-butadiene.
(1) Patent document 1 discloses a process for producing perfluorinated olefins by allowing a perfluorinated alkyl halide to react with a Grignard reagent at a temperature of about from −60° C. to 200° C.
(2) Patent document 2 discloses a process for producing hexafluoro-1,3-butadiene by eliminating iodine fluoride from ICF2CF2CF2CF2I by the use of a Mg, Zn, Cd or Li organic metal compound in the presence of a hydrocarbon non-proton solvent or in the presence of a non-proton polar solvent such as ether or cyclic ethers at a temperature of from −80 to 150° C.
(3) Patent document 3 discloses a process for producing hexafluoro-1,3-butadiene by eliminating iodine fluoride from BrCF2CF2CF2CF2I or BrCF2CF2CF2CF2Br by the use of a Mg or Li organometallic compound in the presence of a hydrocarbon neutral solvent or in an ether, cyclic ether or a mixture thereof neutral solvent at a temperature of from −80 to 150° C.
(4) Patent document 4 discloses a process for producing hexafluoro-1,3-butadiene by eliminating iodine fluoride from ICF2CF2CF2CF2I in the presence of metal zinc, and at least one nitrogen containing compound selected from N,N-dimethyl formamide and N-methyl-2-pyrrolidone.
(5) Patent document 5 discloses a process for producing hexafluoro-1,3-butadiene by using, as a raw material, ICF2CF2CF2CF2I or BrCF2CF2CF2CF2Br in an organic solvent in the presence of at least one metal selected from Mg, Zn, Cd, Al, Cu, Na and Li, and RX (X=Cl, Br or I) and/or I2. In this process, RX is added in an amount of 0.05 to 0.5 equivalent based on the α,ω-dihalogenated perfluoroalkane.
(6) Patent document 6 discloses a process for producing hexafluoro-1,3-butadiene by heating or boiling refluxing XCF2CFXCFYCF2X (X=Cl, Br or I, Y=Cl, Br, I or F) together with at least one metal selected from Mg, Zn, Cd, Al, Cu, Na and Li, and halogenated alkyl RX (X=Cl, Br or I) in an organic solvent. In this process, RX, which is a catalyst, is added in an amount of 0.05 to 0.5 equivalent based on tetrahalogenated perfluorobutane.
Patent Document 1: JP-B-S49 (1974)-39648
Patent Document 2: JP-A-S62 (1987)-26340
Patent Document 3: U.S. Pat. No. 2,589,108
Patent Document 4: JP-A-2001-192345
Patent Document 5: JP-A-2001-192346
Patent Document 6: JP-A-2001-192347